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# Debug Tree
This library allows you to build a tree one element at a time and output it as a pretty string.
The tree can easily be output to a `String`, `stdout` or a file.
This is particularly convenient for generating clean output from nested and recursive functions.
* [Recursive Fibonacci Example](#recursive-fibonacci-example)
* [Overview](#overview)
* [More Examples](#more-examples)
* [Multiple Tagged Trees](#multiple-tagged-trees)
* [Nested Functions](#nested-functions)
* [Panic](#panics)
* [Without Macros](#without-macros)
## Recursive Fibonacci Example
Using the `add_branch!()` macro at the start of the `factors()` function, you can generate an entire call tree, with minimal effort.
<!--{ fibonacci.rs | code: rust }-->
```rust
use debug_tree::*;
fn factors(x: usize) {
add_branch!("{}", x); // <~ THE MAGIC LINE
for i in 1..x {
if x % i == 0 {
factors(i);
}
}
}
fn main() {
// output to file at the end of this block
defer_write!("examples/out/fibonacci.txt");
add_branch!("A Fibonacci Tree");
factors(6);
add_leaf!("That's All Folks!");
}
```
<!--{ end }-->
<!--{ out/fibonacci.txt | code }-->
```
A Fibonacci Tree
├╼ 6
│ ├╼ 1
│ ├╼ 2
│ │ └╼ 1
│ └╼ 3
│ └╼ 1
└╼ That's All Folks!
```
<!--{ end }-->
## Overview
- Add a branch
- `add_branch!("Hello, {}", "World")`
- The branch will exit at the end of the current block
- Add a leaf
- `add_leaf!("I am a {}", "leaf")`
- Added to the current scoped branch
- Print a tree, or write it to file at the end of a block
- `defer_print!()`
- `defer_write!("filename.txt")`
- The tree will be empty after these calls
- To prevent clearing, use `defer_peek_print!` and `defer_peek_write!`
- Handle multiple trees using named trees
- `add_branch_to!("A", "I'm a branch on tree 'A'")`
- `add_leaf_to!("A", "I'm a leaf on tree 'A'")`
- `defer_print!("A")`
- `defer_write!("A", "filename.txt")`
- Get a named tree
- `tree("TREE_NAME")`
- Retrieve the pretty-string from a tree
- `tree("TREE_NAME").string()`
- Usage across threads
- `default_tree()` is local to each thread
- Named trees are shared between threads
## More Examples
### Multiple Tagged Trees
If you need multiple, separated trees you can use a name tag.
<!--{ multiple_trees.rs | code: rust }-->
```rust
use debug_tree::*;
fn populate(tree_name: &str, n_children: usize) {
add_branch_to!(tree_name, "{} TREE", tree_name);
for _ in 0..n_children {
populate(tree_name, n_children / 2);
}
}
fn main() {
// Override tree config (just for "B")
let b_tree = tree("B");
b_tree.set_config_override(
TreeConfig::new()
.indent(4)
.symbols(TreeSymbols::with_rounded().leaf("> ")),
);
defer_write!(b_tree, "examples/out/multiple_trees_B.txt");
defer_write!("A", "examples/out/multiple_trees_A.txt");
populate("A", 2);
populate("B", 3);
}
```
<!--{ end }-->
<!--{ out/multiple_trees_A.txt | code }-->
```
A TREE
├╼ A TREE
│ └╼ A TREE
└╼ A TREE
└╼ A TREE
```
<!--{ end }-->
<!--{ out/multiple_trees_B.txt | code }-->
```
B TREE
├──> B TREE
│ ╰──> B TREE
├──> B TREE
│ ╰──> B TREE
╰──> B TREE
╰──> B TREE
```
<!--{ end }-->
### Nested Functions
Branches also make nested function calls a lot easier to follow.
<!--{ nested.rs | code: rust }-->
```rust
use debug_tree::*;
fn a() {
add_branch!("a");
b();
c();
}
fn b() {
add_branch!("b");
c();
}
fn c() {
add_branch!("c");
add_leaf!("Nothing to see here");
}
fn main() {
defer_write!("examples/out/nested.txt");
a();
}
```
<!--{ end }-->
<!--{ out/nested.txt | code }-->
```
a
├╼ b
│ └╼ c
│ └╼ Nothing to see here
└╼ c
└╼ Nothing to see here
```
<!--{ end }-->
### Line Breaks
Newlines in multi-line strings are automatically indented.
<!--{ multi_line.rs | code: rust }-->
```rust
use debug_tree::*;
fn main() {
// output to file at the end of this block
defer_write!("examples/out/multi_line.txt");
add_branch!("1");
add_leaf!("1.1\nAnother line...\n... and one more line");
add_leaf!("1.2");
}
```
<!--{ end }-->
<!--{ out/multi_line.txt | code }-->
```
1
├╼ 1.1
│ Another line...
│ ... and one more line
└╼ 1.2
```
<!--{ end }-->
### Panics
Even if there is a panic, the tree is not lost!
The `defer_` functions were introduced to allow the tree
to be printed our written to file in the case of a `panic!` or early return.
<!--{ panic.rs | code: rust }-->
```rust
use debug_tree::*;
fn i_will_panic() {
add_branch!("Here are my last words");
add_leaf!("Stay calm, and try not to panic");
panic!("I told you so...")
}
fn main() {
// output to file at the end of this block
defer_write!("examples/out/panic.txt");
// print at the end of this block
{
add_branch!("By using the 'defer_' functions");
add_branch!("Output will still be generated");
add_branch!("Otherwise you might lose your valuable tree!");
}
add_branch!("Now for something crazy...");
i_will_panic();
}
```
<!--{ end }-->
<!--{ out/panic.txt | code }-->
```
By using the 'defer_' functions
└╼ Output will still be generated
└╼ Otherwise you might lose your valuable tree!
Now for something crazy...
└╼ Here are my last words
└╼ Stay calm, and try not to panic
```
<!--{ end }-->
### Without Macros
If you prefer not using macros, you can construct `TreeBuilder`s manually.
<!--{ no_macros.rs | code: rust }-->
```rust
use debug_tree::TreeBuilder;
fn main() {
// Make a new tree.
let tree = TreeBuilder::new();
// Add a scoped branch. The next item added will belong to the branch.
let mut branch = tree.add_branch("1 Branch");
// Add a leaf to the current branch
tree.add_leaf("1.1 Child");
// Leave scope early
branch.release();
tree.add_leaf("2 Sibling");
// output to file
tree.write("examples/out/no_macros.txt").ok(); // Write and flush.
}
```
<!--{ end }-->
<!--{ out/no_macros.txt | code }-->
```
1 Branch
└╼ 1.1 Child
2 Sibling
```
<!--{ end }-->